Wheel case for a vibratory apparatus

ABSTRACT

A sealed wheel case is provided for use with a vibratory device for vibrating aggregate material. The vibratory device includes a frame and a rotating shaft extending transversely across the frame, with the shaft having a wheel. The sealed wheel case includes a housing having a base, a peripheral sidewall, and a cover. The housing is sized to receive therein the wheel and is further adapted to house therein a quantity of lubricating oil for lubricating the wheel. A plurality of attachment bolts are provided for securing the housing to the frame. Each of the attachment bolts includes a shank, an inner end disposed within the wheel case and having an inner contact surface, an inner control washer disposed between the inner contact surface and the housing base, with the inner control washer having a first predetermined thickness. The inner control washer includes an aperture therethrough sized to form with the bolt shank an annular cavity, and an O-ring is provided which is sized for insertion in the annular cavity, with the O-ring having a second predetermined thickness greater than the first predetermined thickness. The bolt further includes an outer end disposed outside the wheel case and having an outer contact surface adjacent the frame. Accordingly, in response to securement of each attachment bolt each O-ring is compressed to substantially fill its adjacent annular cavity, thereby preventing the lubricant from escaping the housing.

FIELD OF THE INVENTION

The present invention relates to vibratory devices such as vibratingscreens for classifying aggregate and vibratory feeders for feedingaggregate to crushing and processing devices. More specifically, thepresent invention relates to an improved wheel case for housing therotating components of the vibratory devices and for protecting thosecomponents from the loss of lubricant and/or from the ingress ofcontaminants.

BACKGROUND OF THE INVENTION

Vibrating screen devices and vibrating feeder devices are generally wellknown in the art. On a typical vibrating screening device, a system ofclassifying screens are mounted to a frame which in turn is supported ona system of springs. At or near the center of the device is aneccentrically weighted shaft unit, typically having one, two, or threeor more rotating and eccentrically weighted shafts. On a multi-shaftunit, the shafts may be counter-rotating such that the eccentric weightsare oriented in the same direction twice each revolution. This causesthe screen to vibrate, which aids the classifying effects of the screendevice. On a vibrating feeder, a similar shaft unit vibrates the feedtrough or chute, which “throws” the aggregate contained in the trough ina desired direction. An example of such a device can be found in U.S.Pat. No. 4,340,469 issued to Archer.

The ends of the rotating shafts are supported by bearings, and eachshaft includes a drive wheel or gear. The shaft drive gears areoperatively coupled to an external drive motor. The eccentric weightsare typically attached to the ends of the shafts adjacent the drivewheels. The bearings and the drive wheels require constant lubrication,and thus such components are disposed within a wheel housing or casecontaining a quantity of oil or other suitable lubricating fluid. Thewheel case is typically bolted to the frame of the vibratory device.

Historically, conventional cap screws have been used to secure the wheelcase to the frame of the vibratory device. However, due to the constantvibration, coupled with the constant exposure of the cap screws to thelubricating oil, such conventional cap screws are subject to loosening.The loosened cap screws provide a convenient avenue for oil loss, andalso provide a convenient avenue for the ingress of dirt, water, andother contaminants. Moreover, the cap screws are not readily accessiblefor the purposes of re-tightening.

Accordingly, threadless fasteners have been used, such as the threadlessfastener sold under the trade name Huckbolt® manufactured by the FederalMogul Corporation. Such a fastener has a threadless collar that ispressed onto the bolt shank using hydraulic means. The collar engages aseries of annular rings spaced along the bolt shank. Such boltstypically provide consistent clamping force and exhibit high resistanceto loosening in most applications. However, such bolts may experienceloosening when used in highly lubricated, vibrating environments, thusleading to the leakage problems outlined above. Such bolts are noteasily re-tightened, and as outlined above, it is not easy to access thesecuring bolts in any event.

In addition to the problems with oil loss and contaminant ingress, bothof which lead to premature failure of the gears and/or the bearingshoused within the wheel case, a loose bolt also causes the holes throughthe bolted components to enlarge, thus accelerating the loss of oil orthe ingress of contaminants. Moreover, loose bolts permit small piecesof aggregate to become lodged between the various bolted components,rendering it impossible to securely bolt the components together withoutcompletely disassembling and cleaning the device.

A similar leakage problem may be created where the spindles, whichsupport the rotatable shafts, are secured to the frame. The spindles aretypically disposed within the wheel case such that the shaft bearingsare exposed to a constant supply of lubricating oil. Each spindleincludes a mounting flange, and an O-ring seal may be provided under themounting flange. However, the cap screws used to secure the spindle tothe frame may loosen in a manner similar to the problem described above,leading to similar problems.

As mentioned above, at least one of the shafts is operatively coupled toan external drive system. Typically, one of the shafts is extendedthrough the wheel case cover for connection to a drive motor. Thispenetration through the wheel case must be sealed. Due to deflections atthe end of the shaft caused by the extreme operating conditions, the endof the shaft typically experiences “runout” which typically causespremature breakdown of the seal. Although labyrinth seals have beenemployed, a typical labyrinth seal includes a weep hole for captured oilto escape back into the sealed area. Under the extreme operatingconditions of the wheel case, in which the rotating eccentric weightscontact the oil supply at velocities in excess of 5000 feet per second,the resulting oil agitation throws oil through the weep hole, causinglubricant loss. Consequently, the seal becomes one additional path oflubricant loss or contaminant ingress.

Accordingly, an improved wheel case having an improved fastening systemless prone to loosening and leakage is desired. It is also desired tohave an improved wheel case which exhibits better lubricant retentioncharacteristics than prior art wheel cases.

SUMMARY OF THE INVENTION

According to one aspect of the invention, and for use with a vibratorydevice for vibrating aggregate material, the device having a frame and arotating shaft extending transversely across the frame, the shaft havinga wheel, a sealed wheel case comprises a housing having a base, aperipheral sidewall, and a cover. The housing is sized to receivetherein the wheel and is further adapted to house therein a quantity oflubricating oil for lubricating the wheel. A plurality of attachmentbolts are provided for securing the housing to the frame. Each of theattachment bolts includes a shank, an inner end disposed within thewheel case and having an inner contact surface, an inner control washerdisposed between the inner contact surface and the housing base, withthe inner control washer having a first predetermined thickness. Theinner control washer includes an aperture therethrough sized to formwith the bolt shank an annular cavity, and an O-ring is provided whichis sized for insertion in the annular cavity, with the O-ring having asecond predetermined thickness greater than the first predeterminedthickness. The bolt further includes an outer end disposed outside thewheel case and having an outer contact surface adjacent the frame.Accordingly, in response to securement of each attachment bolt eachO-ring is compressed to substantially fill its adjacent annular cavity,thereby preventing the lubricant from escaping the housing.

In further accordance with a preferred embodiment, the second thicknessis approximately thirty percent (30%) greater than the first thickness.Still preferably, the first thickness is approximately 0.11 inches, andthe second thickness is approximately 0.14 inches. Each attachment boltis preferably a non-threaded huckbolt.

In further accordance with a preferred embodiment, the second thicknessis approximately thirty percent (30%) greater than the first thickness.Still preferably, the first thickness is approximately 0.11 inches, andthe second thickness is approximately 0.14 inches. Each attachment boltis preferably a non-threaded fastener having a pressed on collar, suchas a Huckbolt®.

According to another aspect of the invention, a sealed attachment boltis provided for securing the base of a sealed housing to a frame, withthe housing being adapted to hold a quantity of lubricant. Theattachment bolt comprises a shank, an inner end disposed within thehousing and having an inner contact surface, and an inner control washerdisposed between the inner contact surface and the housing base. Theinner control washer includes a first predetermined thickness andfurther includes an aperture therethrough sized to form with the boltshank an annular cavity. An O-ring is provided which is sized forinsertion in the annular cavity. The O-ring includes a secondpredetermined thickness greater than the first predetermined thickness.The bolt further includes an outer end disposed outside the wheel caseand having an outer contact surface adjacent the frame. Accordingly, inresponse to securement of each attachment bolt each O-ring is compressedto substantially fill its adjacent annular cavity, thereby preventingthe lubricant from escaping the housing.

According to yet another aspect of the invention, on a vibratory devicefor vibrating aggregate material, with the vibratory device having aframe and a rotating shaft extending transversely across the frame andhaving a wheel, a sealed wheel case comprises a housing having a base, aperipheral sidewall, and a cover. The housing is sized to receivetherein the wheel and is further adapted to house therein a quantity oflubricating oil for lubricating the wheel. A plurality of attachmentbolts are provided for securing the housing to the frame. Each of theattachment bolts includes a shank, an inner end disposed within thewheel case and having an inner contact surface, and an outer enddisposed outside the wheel case and having an outer contact surfaceadjacent the frame. A compression control washer is disposed between theinner contact surface and the outer contact surface, with thecompression control washer having a first predetermined thickness andfurther having an apertute therethrough sized to form with the boltshank an annular cavity. An O-ring sized for insertion in the annularcavity, with the O-ring having a second predetermined thickness greaterthan the first predetermined thickness. Accordingly, in response tosecurement of to each attachment bolt each O-ring is compressed tosubstantially fill its adjacent annular cavity, thereby preventing thelubricant from escaping the housing.

According to a still further aspect of the invention, a sealed wheelcase is provided for use with a vibratory device for vibrating aggregatematerial, with the vibratory device having a frame and a rotating shaftextending transversely across the frame and having a wheel. A drivenportion of the shaft is operatively coupled to a drive system. Thesealed wheel case comprises a housing having a base, a peripheralsidewall, and a cover. The housing is sized to receive therein the wheeland is further adapted to house therein a quantity of lubricating oilfor lubricating the wheel. The cover includes an aperture adapted toreceive therethrough the shaft driven portion. A seal operativelyconnected to the shaft adjacent the wheel case aperture, and an annularbaffle is mounted to the housing cover within the wheel case. Theannular baffle generally surrounds the seal. A plurality of sealedattachment bolts are provided for securing the housing to the frame.

The seal at the cover aperture preferably is a labyrinth seal. Theannular baffle preferably includes an inner edge, with the inner edgebeing disposed adjacent the wheel to form a gap therebetween.

According to a further aspect of the invention, on a vibratory devicefor vibrating aggregate material having a frame and a rotating shaftextending transversely across the frame and having a wheel connected tothe rotating shaft, with a driven portion of the shaft being operativelycoupled to a drive system, a sealed wheel case is provided comprising ahousing having a base, a peripheral sidewall, and a cover. The housingis sized to receive therein the wheel and is further adapted to housetherein a quantity of lubricating oil for lubricating the wheel. Thecover including an aperture adapted to receive therethrough the shaftdriven portion. A seal is operatively connected to the shaft adjacentthe wheel case aperture. Means, carried by the housing cover, areprovided for isolating the seal within the wheel case, and a pluralityof sealed attachment bolts are provided for securing the housing to theframe.

According to a still further aspect of the invention, on a sealedhousing attached to a frame, with the housing being adapted to hold aquantity of lubricant, a sealed attachment bolt is provided whichcomprises a shank, an inner end disposed within the housing and havingan inner contact surface, an outer end disposed outside the housing andhaving an outer contact surface adjacent the frame, an outer controlwasher disposed between the outer contact surface and the frame, theouter control washer having a first predetermined thickness and furtherhaving an aperture therethrough sized to form with the bolt shank anannular cavity, and an O-ring sized for insertion in the annular cavity,the O-ring having a second predetermined thickness greater than thefirst predetermined thickness. Accordingly, in response to securement ofeach attachment bolt each O-ring is compressed to substantially fill itsadjacent annular cavity, thereby preventing the lubricant from escapingthe housing.

According to a still further aspect of the invention, on a sealed wheelcase mounted to a frame and having a rotating shaft supported inside thewheel case on a spindle, with the wheel case being adapted to hold aquantity of lubricant, an attachment bolt is provided which comprises ashank, an inner end disposed within the wheel case and having an innercontact surface bearing on a portion of the spindle, an outer enddisposed outside the wheel case and having an outer contact surfaceadjacent the frame, a control washer disposed between the inner contactsurface and the spindle, with the control washer having a firstpredetermined thickness and further having an aperture therethroughsized to form with the bolt shank an annular cavity, and an O-ring sizedfor insertion in the annular cavity, with the O-ring having a secondpredetermined thickness greater than the first predetermined thickness.Accordingly, in response to securement of each attachment bolt eachO-ring is compressed to substantially fill its adjacent annular cavity,thereby preventing the lubricant from escaping the wheel case. Thecontrol washer may include a truncated side portion, and the innercontact surface may include a bolt head, with the truncated side portionbeing adapted to permit the bolt head to be disposed adjacent anextended portion of the spindle, whereby upon the application of atwisting torque to the bolt from the outer end rotation of the bolt headis prevented.

The aforementioned features and advantages, in addition to otherfeatures and advantages, will become readily apparent to those skilledin the art upon a reading of the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a fragmentary schematic elevational view of a vibratory devicehaving a three shaft sealed wheel case attached to the vibratory device,the wheel case being shown with a portion cut away to reveal the wheelsdisposed therein;

FIG. 2 is an enlarged fragmentary cross-sectional view taken along line2—2 of FIG. 1 and illustrating a wheel case constructed in accordancewith certain teachings of the present invention;

FIG. 3 is a further enlarged fragmentary cross-sectional view of asealed attachment bolt assembled in accordance with the teachings of thepresent invention;

FIG. 4 is a fragmentary cross sectional view of another sealedattachment bolt constructed in accordance with the teachings of thepresent invention;

FIG. 5 is a fragmentary cross sectional view of another sealedattachment bolt constructed in accordance with the teachings of thepresent invention;

FIG. 6 is a fragmentary cross sectional view of another sealedattachment bolt constructed in accordance with the teachings of thepresent invention;

FIG. 7 is a fragmentary cross sectional view of another sealedattachment bolt constructed in accordance with the teachings of thepresent invention;

FIG. 8 is a fragmentary cross sectional view of another sealedattachment bolt constructed in accordance with the teachings of thepresent invention;

FIG. 9 is an enlarged elevational view of a clipped washer for use withthe attachment bolt of FIG. 8; and

FIG. 10 is an enlarged fragmentary view similar to FIG. 2 butillustrating a seal around the penetration of the shaft through thewheel case housing constructed in accordance with the teachings of thepresent invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The embodiment described herein is not intended to be exhaustive or tolimit the scope of the invention to the precise form disclosed. Thefollowing embodiment has been chosen and described in order to bestexplain the principles of the invention and to enable others skilled inthe art to follow its teachings.

Referring now to the drawings, an improved wheel case generallyindicated by the reference numeral 10 is shown in FIGS. 1 and 2 in apreferred environment of use, namely, mounted on a vibrating screendevice 12 of the type commonly employed in the art to process aggregatematerials by classifying and/or separating the aggregate materialaccording to size. Persons of ordinary skill in the art will recognizethat the improved wheel case 10 may also be used on other devices, suchas vibrating trough feeders, as well as other devices benefiting fromthe features to be discussed below.

As shown in FIGS. 1 and 2, the vibrating screen device 12 typicallyincludes a frame 14 supporting a deck 16 to which is mounted one or moreclassifying screens (not shown) of the type commonly employed for suchpurposes. A pair of opposing sidewalls 18 are secured to the frame 14,and one or more shafts 20, each housed in a housing 22, are rotatablymounted to the frame 14 and extend between the sidewalls 18.

As shown in FIGS. 1 and 2, one or more shafts 20 are provided, forexample shafts 20 a, 20 b, and 20 c. It will be understood that only asingle shaft 20 will be discussed in detail. The shaft 20 includes anend 24 which is rotatably mounted to a spindle 26 by a bearing assembly28. Attached to the end of the shaft 20 is wheel 29 having an eccentricweight 30 and a gear 32, which gear 32 may be either a drive gear or adriven gear as required. Although only one end 24 of the shaft 20 it isshown, it will be understood that the other end (not shown) of the shaft20 is substantially similar and is rotatably mounted to the opposingsidewall 18 of the frame 14 in a similar manner. The device 12 may alsoinclude a plurality of additional side members or stiffeners 34 asrequired.

As shown in FIG. 2, the end 24 of the shaft 20, along with the spindle26, the bearing assembly 28, the eccentric weight 30 and the gear 32 areall disposed within the wheel case 10. It will be understood that thewheel case 10 is adapted to contain therein a quantity of lubricatingoil for the purposes of supplying lubricant to the bearing assembly 28,the gear 32, and to any other components housed within the wheel case 10as required. It will also be understood that a portion of the eccentricweight 30 and/or a portion of the gear 32 comes into contact with,agitates, and distributes the oil about an interior 36 of the wheel case10.

As shown in FIGS. 1 and 2, the wheel case 10 includes a housing 38having a base 40, a peripheral sidewall 42 extending outwardly away fromthe base 40, and a cover 44 attachable to the sidewalls 42 so as toenclose the interior 36. The cover 44 is preferably removable as wouldbe known to those of skill in the art in order to gain access to thevarious components housed within the wheel case 10. A plurality ofattachment bolts 46 are provided for securing the wheel case 10 to theframe 14 (i.e., by securing the base 40 of the housing 38 to thesidewall 18 and the frame 14).

Although a number of configurations are contemplated for the attachmentbolt 46, the preferred embodiment is shown in FIG. 3. Referring now toFIG. 3, the attachment bolt 46 shown therein includes an inner end 48disposed inside the housing 38 of the wheel case 10, an outer end 50disposed outside the housing 38, and an interconnecting shank 52. Theinner end 48 includes an inner contact surface 54, while the outer end50 includes an outer contact surface 56.

The bolt 46 is preferably a threadless bolt having a pressed on collar58, and preferably the bolt 46 is a threadless bolt sold under the tradename Huckbolt® and is manufactured by the Federal Mogul Corporation.Other suitable fasteners, especially other suitable threadless fastenersand/or other suitable fasteners which may be fastened with a desiredpre-load tension on the bolt 46 may be employed, with the desiredpre-load tension typically being designated by the manufacturer orotherwise determined using well known principles of mechanics. Thecollar 58 is preferably pressed on using a tool, such as a hydraulictool, of the type commonly employed for such installations. The collar58 is retained on the shank 52 by a plurality of annular rings 60 spacedalong a portion of the shank 52.

A pair of compression control washers 62, 64 are provided. The washers62, 64 are preferably 0.108 inches thick, and have a hardness in therange of 38-45 on the Rockwell “C” hardness scale. The washer 62includes an aperture 66 which is greater than the diameter of the shank52 so as to define an annular cavity 68 surrounding the shank 52. Theannular cavity 68 is sized to receive a resilient O-ring seal 70.Similarly, the washer 64 includes an aperture 72 which is greater thanthe diameter of the shank 52 so as to define an annular cavity 74surrounding the shank 52. The annular cavity 74 is sized to receive aresilient O-ring seal 76. The O-rings 70, 76 are preferably thicker thanthe thickness of the washers 62, 64, and are preferably 0.140 inchesthick. Still preferably, the O-rings may be manufactured of a resilientrubber compound, such as nitrile rubber.

The washer 62 and the O-ring 70 are disposed adjacent the outer contactsurface 56, while the washer 64 and the O-ring 76 are disposed adjacentthe inside contact surface 54, inside the wheel case 10. An additionalwasher 78 may be employed, but the use of such is optional.

In operation, the housing 38 and the stiffeners 34 are positioned forattachment to the sidewall 18 of the frame 14 as shown in FIG. 3. Thewasher 62 and the O-ring 70 are positioned on the bolt 46 adjacent theouter contact surface 56. The inner end 48 of the attachment bolt 46 isthen inserted into the wheel case 10 from the opposite side of thesidewall 18. The washer 64 and the O-ring 76 are placed along the shank52, and then the collar 58 is applied using the above referenced tool ina known manner. The tool draws the inner end 48 (typically by pulling ona break-away portion, which is not shown but which is releasable along afrangible connection line 80). As stated above, the optional washer 78may be included as shown.

In the process of securing the bolt 46, the inner and outer contactsurfaces 54, 56 are drawn together, which compresses the O-rings 70, 76such that they substantially fill their respective annular cavities 68,74. The ratio between the thickness of the O-rings 70, 76 and thethickness of their associated washer 62, 64, allows for the Wrings to becompressed a desired amount to maximize their sealing capacities whilepreventing inadvertent damage to the O-rings via over-compression.

The embodiment shown in FIG. 4 is similar to that shown in FIG. 3, butit excludes the inner washer 64 and the inner O-ring 76, and excludesthe optional washer 78.

The embodiment shown in FIG. 5 also is similar to that shown in FIG. 3,but it excludes the outer washer 62 and the outer O-ring 70, andincludes the optional washer 78.

The embodiment shown in FIG. 6 is similar to that shown in FIG. 5, butthe inner washer 64 is sized such that the inner O-ring 76 is disposedin an annular cavity 65 defined in part by an outer perimeter 67 of thewasher 64. The embodiment of FIG. 6 also includes an optional washer 78.

The embodiment shown in FIG. 7 is similar to that shown in FIG. 6, butincludes an outer washer 62 sized such that the outer O-ring 70 isdisposed in an annular cavity 69 defined in part by an outer perimeter71 of the washer 62. The optional washer 78 is excluded.

Referring now to FIGS. 8 and 9, an attachment bolt 146 is shown, such asan attachment bolt used to secure the spindle 26 to the frame 14 in anarea of low lateral clearance. The bolt 146 is preferably a conventionalcap screw, although other suitable fasteners may be employed. The bolt146 includes an inner washer 164 having an aperture 172 defining withthe bolt shank 152 an annular cavity 174. A pair of compressible O-rings176 a, 176 b are provided for insertion in the cavity 174 in stackedarrangement.

The O-rings 176 a, 176 b will preferably have a stacked height totalingapproximately 30% greater than the thickness of the washer 164. It willbe noted in FIG. 9, that the washer 164 includes a truncated sideportion 180, thereby permitting an inner end 150 of the attachment bolt146 to be positioned in close proximity to an extended portion 182 ofthe spindle 26, such that upon application of a torque to an outer end148, rotation of the bolt 146 is prevented. The O-rings 176 a, 176 bcooperate to prevent lubricant from leaking out of the wheel case 10along the shank 152 of the bolt 146.

Referring now to FIG. 10, it will be appreciated that at least one ofthe shafts 20, such as, for example, the shaft 20 b, will include aportion 100 extending out of the cover 44 of the wheel case 10 foroperative engagement with an external drive source (not shown).Accordingly, the cover 44 includes an aperture 102 having a seal 104.Preferably, the seal 104 is a labyrinth seal, such as a ProTech®labyrinth seal manufactured by JM Clipper. The seal 104 includes atleast one weep hole 106. An annular cylindrical baffle 108 is secured toan inner surface 109 of the cover 44, and is spaced outwardly from andgenerally surrounds the aperture 102 and the seal 104. It will be notedthat the baffle 108 includes an inner end 110 which is disposedgenerally adjacent to the wheel 29 so as to define a relatively smalland generally annular gap 112 therebetween.

It will be appreciated that, during operation of the device 12,splashing and otherwise agitated oil (not shown) is shielded from theseal 104, the weep hole 106 and the aperture 102 by the annular baffle108. The sealing properties are enhanced by the relatively small size ofthe gap 112.

Numerous modifications and alternative embodiments of the invention willbe apparent to those skilled in the art in view of the foregoingdescription. Accordingly, this description is to be construed asillustrative only and is for the purpose of teaching those skilled inthe art the best mode of carrying out the invention. The details of thestructure may be varied substantially without departing from the spiritof the invention, and the exclusive use of all modifications which comewithin the scope of the appended claims is reserved.

What is claimed:
 1. A sealed wheel case for use on a vibratory device for vibrating aggregate material, the vibratory device having a frame and a rotating shaft extending transversely across the frame and having a wheel, the sealed wheel case comprising: a housing having a base, a peripheral sidewall, and a cover, the housing being sized to receive therein the wheel and further being adapted to house therein a quantity of lubricating oil for lubricating the wheel; and a plurality of threadless attachment bolts for securing the housing to the frame, each of the attachment bolts including: a shank; an inner end having a pressed on collar, the inner end and the pressed on collar disposed within the housing and having an inner contact surface, the inner contact surface defined by the pressed on collar; an outer end disposed outside the wheel case and having an outer contact surface adjacent the frame; an inner control washer disposed between the inner contact surface and the housing base, the inner control washer having a first predetermined thickness and further having an aperture therethrough sized to form with the bolt shank an inner annular cavity; and an O-ring sized for insertion in the inner annular cavity, the O-ring having a second predetermined thickness greater than the first predetermined thickness; an outer control washer disposed between the outer contact surface and the frame, the outer control washer having a third predetermined thickness and further having an aperture therethrough sized to form with the bolt shank an outer annular cavity, and an outer O-ring sized for insertion in the outer annular cavity, the outer O-ring having a fourth predetermined thickness greater than the third predetermined thickness; whereby in response to securement of each attachment bolt by attaching the pressed on collar each O-ring is compressed to substantially fill its adjacent annular cavity, thereby preventing the lubricant from escaping the housing and further preventing the pressed on collar from loosening.
 2. The sealed wheel case of claim 1, wherein the second thickness is approximately thirty percent (30%) greater than the first thickness.
 3. The sealed wheel case of claim 1, wherein the first thickness is approximately 0.11 inches, and further wherein the second thickness is approximately 0.14 inches.
 4. The sealed wheel case of claim 1, wherein the fourth thickness is approximately thirty percent (30%) greater than the third thickness.
 5. The sealed wheel case of claim 1, wherein the third thickness is approximately 0.11 inches, and further wherein the fourth thickness is approximately 0.14 inches.
 6. The sealed wheel case of claim 1, wherein the first and third predetermined thicknesses are equal, and further wherein the second and fourth predetermined thicknesses are equal.
 7. For securing the base of a sealed housing to a frame, the housing being adapted to hold a quantity of lubricant, an attachment bolt comprising: a threadless shank; an inner end including a threadless pressed-on collar, the inner end and the pressed-on collar disposed within the housing and exposed to the lubricant, the pressed-on collar having an inner contact surface; an inner control washer disposed between the inner contact surface and the housing base, the inner control washer having a first predetermined thickness and further having an aperture therethrough sized to form with the bolt shank an inner annular cavity; an inner O-ring sized for insertion in the inner annular cavity, the inner O-ring having a second predetermined thickness greater than the first predetermined thickness; and an outer end disposed outside the wheel case and having an outer contact surface adjacent the frame; an outer control washer disposed between the outer contact surface and the frame, the outer control washer having a third predetermined thickness and further having an aperture therethrough sized to form with the bolt shank an outer annular cavity; an outer O-ring sized for insertion in the outer annular cavity, the outer O-ring having a fourth predetermined thickness greater than the third predetermined thickness; whereby in response to securement of each attachment bolt each O-ring is compressed to substantially fill its adjacent annular cavity, thereby preventing the lubricant from escaping the housing.
 8. The attachment bolt of claim 7, wherein the second thickness is approximately thirty percent (30%) greater than the first thickness.
 9. The attachment bolt of claim 7, wherein the first thickness is approximately 0.11 inches, and further wherein the second thickness is approximately 0.14 inches.
 10. The attachment bolt of claim 7, (therein the fourth thickness is approximately thirty percent (30%) greater than the third thickness.
 11. The attachment bolt of claims 7, wherein the third thickness is approximately 0.11 inches, and further wherein the fourth thickness is approximately 0.14 inches.
 12. The attachment bolt of claim 7, wherein the first and third predetermined thicknesses are equal, and further wherein the second and fourth predetermined thicknesses are equal.
 13. A sealed wheel case for use on a vibratory device for vibrating aggregate material, the vibratory device having a frame and a rotating shaft extending transversely across the frame and having a wheel, the sealed wheel case, comprising: a housing having a base, a peripheral sidewall, and a cover, the housing being sized to receive therein the wheel and further being adapted to house therein a quantity of lubricating oil for lubricating the wheel; and a plurality of double sealed attachment bolts for securing the housing to the frame, each of the attachment bolts including: a threadless shank having a series of non-advancing grooves; an inner end having a pressed on collar adapted to engage the non-advancing grooves, the pressed on collar disposed within the wheel case, the pressed on collar having an inner contact surface; an outer end disposed outside the wheel case and having an outer contact surface adjacent the frame; a pair of compression control washers, one of the compression control washers disposed between the inner contact surface and the housing, the other compression control washer disposed between the outer contact surface and the frame, each compression control washer having a first predetermined thickness and further having an aperture therethrough sized to form with the bolt shank an annular cavity; and an O-ring sized for insertion in each annular cavity, each O-ring having a second predetermined thickness greater than the first predetermined thickness; whereby in response to securement of each attachment bolt each O-ring is compressed to substantially fill its adjacent annular cavity, thereby providing a double seal along the shank of each attachment bolt and thereby preventing the lubricant from escaping the housing.
 14. For securing the base of a sealed housing to a frame, the housing being adapted to hold a quantity of lubricant, double sealed and threadless attachment bolt comprising: a shank, the shank having a plurality of non-advancing grooves; an inner end disposed within the housing and having an inner contact surface defined by a pressed on collar, the collar arranged for frictional and non-threaded engagement with the grooves; an outer end disposed outside the wheel case and having an outer contact surface adjacent the frame; an inner control washer disposed between the inner contact surface and a base portion of the housing, the inner control washer having a predetermined thickness and further having an aperture therethrough sized to form with the bolt shank an annular cavity; an outer control washer disposed between the outer contact surface and the frame, the outer control washer having a predetermined thickness and further having an aperture therethrough sized to form with the bolt shank another annular cavity; and an O-ring sized for insertion in each annular cavity, each O-ring having a thickness approximately 30% greater than the predetermined thickness of its corresponding control washer; whereby in response to securement of each attachment bolt each O-ring is compressed to substantially fill its adjacent annular cavity, thereby preventing the lubricant from escaping the housing. 